WO2023130636A1

WO2023130636A1 - Uniaxial crystal-based phase contrast microscopy module, device and method

Info

Publication number: WO2023130636A1
Application number: PCT/CN2022/091660
Authority: WO
Inventors: 朱文国; 赵梦婷; 余健辉; 陈哲
Original assignee: 暨南大学
Priority date: 2022-01-10
Filing date: 2022-05-23
Publication date: 2023-07-13
Also published as: CN114527559B; CN114527559A

Abstract

Disclosed are a uniaxial crystal-based phase contrast microscopy module, device and method. The module comprises: a first polarizing plate, a second polarizing plate, and a uniaxial crystal arranged therebetween. Polarization states of the first polarizing plate and the second polarizing plate are orthogonal or parallel. The first polarizing plate is used for converting incident light carrying information of an object to be detected into linearly polarized light; the uniaxial crystal is used for enabling, on the basis of a photonic spin Hall effect and/or an angular dispersion effect, left-handed circularly polarized light and right-handed circularly polarized light generated by the linearly polarized light to generate displacements in opposite directions; and the second polarizing plate is used for performing sum or difference operation on a left-handed circularly polarized light field and a right-handed circularly polarized light field, so that when the displacements of the left-handed circularly polarized light and the right-handed circularly polarized light are much less than a spot size, a transmitted light field thereof is a first-order differential of the original incident light field. The present method can be used for edge enhancement of object strength information and visualization of object phase information. Compared with a traditional phase contrast microscopy technology, the present invention is more visual, convenient and time-saving.

Description

Phase-contrast microscopy module, device and method based on uniaxial crystal

technical field

The invention relates to the fields of optical imaging and optical information processing, in particular to a phase contrast microscope module, method and equipment based on uniaxial crystals.

Background technique

The fast and reliable detection and identification of objects via light waves is the basis for optical imaging, machine learning and artificial intelligence. Optical phase contrast microscopy can not only realize the edge enhancement of object intensity information, but also convert the phase information of transparent objects into intensity patterns. Therefore, optical phase contrast microscopy has broad application prospects in the fields of optical high-contrast imaging, biomedicine, face recognition, and optical simulation computing.

At present, there are many methods of optical phase contrast microscopy, and the commonly used methods include Zernike phase contrast microscopy, Nomarski differential interference phase contrast imaging, and optical space differential microscopy. Traditional Zernike phase-contrast microscopic imaging and Nomarski differential interference phase-contrast imaging rely on complex modulation in space or spatial frequency domains, resulting in complex systems and difficulties in optical alignment and adjustment. Optical space differential microscopy imaging can realize phase-contrast microscopy by constructing a suitable transfer function and performing differential processing on the light field. Optical spatial differential microscopy has attracted extensive attention due to its wide operating frequency band, isotropic edge enhancement and relatively compact optical system. However, at present, optical spatial differentiators are mainly based on micro-nano structures such as metal surface plasmons and artificial metasurfaces, which are expensive to manufacture and difficult to produce on a large scale.

Contents of the invention

In view of this, the object of the present invention is to provide a phase contrast microscope module, equipment and method based on uniaxial crystals to solve the above problems.

An embodiment of the present invention provides a phase contrast microscope module based on a uniaxial crystal, which includes:

a first polarizer, a second polarizer and a uniaxial crystal;

The polarization states of the first polarizer and the second polarizer are orthogonal or parallel, and the uniaxial crystal is arranged between the first polarizer and the second polarizer; wherein:

The first polarizer is used to convert the received incident light carrying the information of the object to be measured into linearly polarized light polarized along a specified direction;

The uniaxial crystal is used to displace the left-handed circularly polarized light and the right-handed circularly polarized light generated by the linearly polarized light in opposite directions based on the photon spin Hall effect and/or angle dispersion effect;

The second polarizer is used to perform a sum or difference operation on the left-handed circularly polarized light field and the right-handed circularly polarized light field, so that when the displacement of the left-handed circularly polarized light field and the right-handed circularly polarized light is much smaller than the spot size , the transmitted light field is the first differential of the original incident light field.

Preferably, the uniaxial crystals are yttrium vanadate, lithium niobate, quartz, calcite, BBO uniaxial crystals.

Preferably, the left-handed circularly polarized light and the right-handed circularly polarized light with opposite spin directions generated by the uniaxial crystal have a lateral displacement caused by photon spin splitting.

Preferably, the optical axis of the uniaxial crystal has a certain inclination angle relative to the beam propagation direction, and the displacement can be adjusted by changing the inclination angle.

Preferably, when the polarization states of the first polarizer and the second polarizer are orthogonal, the first-order differential of the incident light field in one dimension is realized;

When the polarization states of the first polarizer and the second polarizer are parallel, the first order differential of the incident light field in two dimensions is realized simultaneously.

An embodiment of the present invention also provides a uniaxial crystal-based phase-contrast microscope, which includes an illumination module, an imaging module, and the above-mentioned phase-contrast microscope module.

Preferably, the imaging module includes a first objective lens, a first focusing lens and a camera, and the phase contrast microscope module is arranged between the first focusing lens and the camera; the first objective lens is arranged on the first Before focusing the lens.

Preferably, the lighting module includes a light source, a second objective lens, and a second focusing lens; wherein, along the propagation direction of incident light, the second objective lens is arranged between the light source and the second focusing lens; the light source For LED, halogen lamp or laser light source.

Preferably, the phase contrast microscopy equipment further includes an object stage; the object stage is arranged between the first focusing lens and the first objective lens.

The embodiment of the present invention also provides a phase contrast microscopy method based on the above uniaxial crystal phase contrast microscopy equipment, which includes:

The light source emits incident light, and after the incident light is collimated by the second objective lens and focused by the second focusing lens on the object to be imaged on the stage, the first signal light is formed;

After the first objective lens collimates the first signal light, it is focused onto the camera by the first focusing lens. Before the signal enters the camera, it passes through the phase contrast microscope module;

The first polarizer transforms the received signal light into linearly polarized light polarized along a specified direction;

The uniaxial crystal is based on the photon spin Hall effect and/or angle dispersion effect, so that the left-handed circularly polarized light and the right-handed circularly polarized light generated by the linearly polarized light are displaced in opposite directions; wherein, the left-handed circularly polarized light and the right-handed circularly polarized light Circularly polarized light has an overlapping region, and the overlapping region contains both left-handed circularly polarized light and right-handed circularly polarized light;

The second polarizer performs a sum or difference operation on the left-handed circularly polarized light field and the right-handed circularly polarized light field to obtain the second signal light. When the displacement of left and right circularly polarized light is much smaller than the spot size, the second signal light is the first order differential of the original incident light field;

A camera records the second signal light to obtain phase contrast information of the object to be imaged.

To sum up, the embodiment of the present invention utilizes the method of spin optics to realize the spatial differential calculation of the input image, which can be used for edge enhancement of object intensity information and visualization of object phase information. Compared with the traditional phase contrast microscopy technology, the phase contrast microscopy technology realized by the embodiment of the present invention is more intuitive, more convenient, and more time-saving, and the embodiment of the present invention can be directly embedded in the existing optical microscopy system, The overall implementation cost is low and easy to integrate.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings used in the implementation will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some implementations of the present invention. As far as the skilled person is concerned, other drawings can also be obtained based on these drawings on the premise of not paying creative work.

Fig. 1 is a schematic structural diagram of a phase contrast microscope module based on a uniaxial crystal provided in the first embodiment of the present invention.

Figure 2(a) shows the spin-splitting shift of right-handed polarized light as a function of incident angle.

Figure 2(b) shows the spin-splitting shift of left-handed polarized light as a function of incident angle. FIG. 3 is a schematic structural diagram of a phase contrast display device based on a uniaxial crystal provided in a second embodiment of the present invention.

Figure 4(a)-Figure 4(d) are phase contrast microscopy detection images based on the theoretical calculation of the photon spin Hall effect.

Fig. 5(a)-Fig. 5(h) are experimental comparison diagrams of phase-contrast microscopic examination of the resolution plate.

Fig. 6(a)-Fig. 4(d) are comparison diagrams of phase-contrast microscopy experiments on onion epidermal cells.

Fig. 7 is a schematic flow chart of the phase contrast microscopy method provided by the third embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to FIG. 1, the first embodiment of the present invention provides a phase contrast microscope module 10 based on uniaxial crystal, which includes:

The first polarizer 11, the second polarizer 12 and the uniaxial crystal 13; the polarization states of the first polarizer 11 and the second polarizer 12 are orthogonal or parallel, and the uniaxial crystal 13 is arranged on the first Between the polarizer 11 and the second polarizer 12; wherein:

The first polarizer 11 is used to transform the received incident light carrying the information of the object to be measured into linearly polarized light polarized along a specified direction.

In this embodiment, the incident light may be light emitted by an incoherent light source or a coherent light source. Before the incident light reaches the first polarizer 11, it needs to pass through the object to be imaged. The imaged object is a transparent object, so that the incident light carries the information of the object.

The uniaxial crystal 13 is used for, based on the photon spin Hall effect and/or angle dispersion effect, causing the left-handed circularly polarized light and the right-handed circularly polarized light generated by the linearly polarized light to be displaced in opposite directions.

Specifically, it can be seen from the photon spin Hall effect that when the beam passes through the surface of a non-uniform medium for reflection and refraction, the photons with opposite spin angular momentum will separate from each other in the direction perpendicular to the incident surface, resulting in spin splitting of the beam Phenomenon. When the beam is incident on the medium, the incident wave function can be expressed as:

(where s represents the spin state of the particle) the output wave function can be expressed as:

In the formula, δ represents the displacement caused by spin splitting. When the incident wave profile is much larger than the spin splitting displacement δ, the above formula can be simplified as

It can be seen from the above formula that the spatial differential is generated due to the opposite displacement ±δ of the spin state, that is, the spatial differential calculation is essentially a photon spin Hall effect. Therefore, the optical spatial differential calculation of the input image can be realized by using the photonic spin Hall effect.

In this embodiment, the uniaxial crystal 13 can be uniaxial crystals such as yttrium vanadate, lithium niobate, quartz, calcite, BBO, etc., of course, it can also be other uniaxial crystals with the same or similar characteristics. Be specific. Taking the uniaxial yttrium vanadate crystal as an example, when a beam of linearly polarized light is incident on the uniaxial yttrium vanadate crystal, a photon spin Hall effect will be generated, in particular, a left-handed circular polarization with opposite spin direction will be generated. Light and right-handed circularly polarized light, the two beams of light with opposite spins produce a spin-split displacement δ in the transverse direction. When the displacement δ is small enough, there will be an overlapping region containing both left-handed circularly polarized light and right-handed circularly polarized light.

In this embodiment, as shown in FIG. 2 , the displacement δ can be adjusted by changing the inclination angle of the uniaxial crystal 13 relative to the normal of the optical axis, where the direction of the optical axis is consistent with the propagation direction of the incident light. As mentioned above, Figure 2(a) shows the spin-splitting displacement of right-handed polarized light as a function of incident angle. Figure 2(b) shows the spin-splitting shift of left-handed polarized light as a function of incident angle.

The second polarizer 12 is used to perform a sum or difference operation on the left-handed circularly polarized light field and the right-handed circularly polarized light field, so that when the displacement of the left-handed circularly polarized light field and the right-handed circularly polarized light is much smaller than the spot size When , the transmitted light field is the first order differential of the original incident light field.

In the present embodiment, when the polarization states of the first polarizer 11 and the second polarizer 12 are orthogonal, the first-order differential in one dimension of the incident light field is realized;

When the polarization states of the first polarizer 11 and the second polarizer 12 are parallel, the first order differential of the incident light field in two dimensions is realized simultaneously.

To sum up, in the phase contrast microscope module 10 provided by this embodiment, when the incident light beam is obliquely incident on the surface of the uniaxial crystal 13 at a certain angle, due to the effect of the refractive index gradient, the photon spin Hall effect will be generated to realize the The spatial differentiation of the input image enables edge enhancement of object intensity information and visualization of object phase information. Compared with the traditional phase-contrast microscopy technique, the phase-contrast microscopy technique implemented in this embodiment is more intuitive, more convenient, and more time-saving.

Furthermore, the phase-contrast microscope module 10 provided in this embodiment can be directly embedded in existing microscope equipment, and the overall implementation cost is low and easy to integrate. Among them, when applied to microscopic equipment, when the phase contrast microscopic module 10 is not inserted, the microscopic equipment can present a clear image, and when the phase contrast microscopic module is inserted, the microscopic equipment can realize edge enhancement and object phase information visualization.

The application of this embodiment in phase contrast microscopy equipment will be described in detail below.

Please refer to FIG. 3 , the second embodiment of the present invention provides a phase-contrast microscope device based on uniaxial crystal, which includes an illumination module, an imaging module, and a phase-contrast microscope module 10 according to any of the above-mentioned embodiments.

Wherein, the imaging module includes a first objective lens 20, a first focusing lens 31 and a camera 32, and the phase contrast microscope module 10 is arranged between the first focusing lens 31 and the camera 32; the first objective lens 20 It is arranged in front of the first focusing lens 31.

Wherein, the camera may be a CCD, a CMOS camera, etc., which are not specifically limited in the present invention.

Wherein, the illumination module includes a light source 40, a second objective lens 50, and a second focusing lens 60, and along the direction of incident light propagation, the second objective lens 50 is arranged between the light source 40 and the second focusing lens 60 .

Wherein, the light source 40 is a light source such as LED, halogen lamp or laser. In particular, the light source 40 is an incoherent light source, such as an LED light source. Compared with laser lighting, LED lighting is more uniform, and the cost of LED is lower.

In this embodiment, the phase contrast microscopy equipment further includes an object stage 70, which is arranged between the second focusing lens 60 and the first objective lens 20, and is used to carry the object to be imaged. object.

In this embodiment, the working principle of the phase contrast microscope is that when the light passes through the object on the stage 70, the images with different details will have a phase difference, and the optical path of each part after focusing with the second focusing lens 60 Different, the light beams are deflected to different degrees. When the two groups of light rays are converged by the first focusing lens 31 and recombined on the same optical path, the direct light and the diffracted light will produce light interference during the propagation process, and the phase difference will become Poor amplitude. When observed by a phase-contrast microscope, the light passing through a colorless transparent body converts the phase difference that cannot be resolved by the human eye into an amplitude difference that the human eye can distinguish. Therefore, phase contrast microscopy equipment is used as an imaging module here. Compared with ordinary microscope imaging, phase contrast imaging is the most effective method for imaging transparent samples. It can obtain the outline details of samples that cannot be seen by ordinary intensity imaging.

In order to facilitate the understanding of the present invention, some practical examples are used below to demonstrate the application of the embodiment of the present invention on image edge enhancement, but it should be understood that these practical applications are only part of the application of the present invention, and cannot be understood as a comprehensive application of the present invention. limit.

Please refer to FIG. 4 . FIG. 4 is an edge detection diagram realized by theoretically calculating the photon spin Hall effect provided by an embodiment of the present invention. Fig. 4 (a) represents the graph on the right-handed component, Fig. 4 (b) represents the graph on the left-handed component, Fig. 4 (c) represents the graph on the x component, Fig. 4 (b) represents the graph on the y component.

Please refer to FIG. 5 , which is a comparison diagram of edge detection obtained when the stage 70 is a resolution plate. Among them, Figure 5(a), (c), (e), (g) are numbers or graphics on the resolution board, and Figure 5(b), (d), (f), (h) are the corresponding edges Detection map. It can be seen from the comparison that the edges of each number and figure can be clearly seen on the finally obtained edge detection map.

Please refer to Figure 6, Figure 6(a) and Figure 6(c) are unstained onion epidermal cells observed. Figure 6(b) and Figure 6(d) are the edge detection diagrams obtained by performing edge detection on onion epidermal cells, where Figure 6(a) corresponds to Figure 6(b), and Figure 6(c) corresponds to Figure 6(d) , the edge of the onion epidermal cells can be clearly seen by contrast.

Please refer to FIG. 7, the third embodiment of the present invention also provides a phase contrast microscopy method based on the phase contrast microscopy equipment of the uniaxial crystal as described above, which includes:

S301, the light source emits incident light, and the incident light is collimated by the second objective lens and focused by the second focusing lens onto the object to be imaged on the stage to form the first signal light;

S302. After the first objective lens collimates the first signal light, it is focused onto the camera by the first focusing lens. Before the signal enters the camera, it passes through the phase contrast microscope module;

S303, the first polarizer transforms the received signal light into linearly polarized light polarized along a specified direction;

S304, based on the photon spin Hall effect and/or angular dispersion effect, the uniaxial crystal causes the left-handed circularly polarized light and the right-handed circularly polarized light generated by the linearly polarized light to be displaced in opposite directions;

S305, the second polarizer is used for the sum or difference calculation of the left-handed circularly polarized light field and the right-handed circularly polarized light field, the transmitted light field of the second polarizer is the first-order differential of the original incident light field, and the second signal light;

S306. The camera records the second signal light to obtain phase contrast information of the object to be imaged.

Preferably, the left-handed circularly polarized light and the right-handed circularly polarized light with opposite spin directions generated by the uniaxial crystal have a displacement generated by photon spin splitting in the transverse direction, and when the displacement is less than a preset threshold, the left-handed circularly polarized light There is an overlapping region between circularly polarized light and right-handed circularly polarized light.

Preferably, the uniaxial crystal is tilted at a certain angle relative to the normal of the optical axis, and the direction of the optical axis is consistent with the propagation direction of the incident light, and the displacement is adjusted by changing the tilt angle of the uniaxial crystal relative to the normal of the optical axis .

To sum up, the embodiment of the present invention utilizes the method of spin optics to realize the spatial differential calculation of the input image, which can be used for edge enhancement of object intensity information and visualization of object phase information. Compared with the traditional phase contrast microscopy technique, the phase contrast microscopy technique implemented in the embodiment of the present invention is more intuitive, more convenient, and more time-saving.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

A phase contrast microscopy module based on uniaxial crystals, characterized in that it comprises:

a first polarizer, a second polarizer and a uniaxial crystal;

The polarization states of the first polarizer and the second polarizer are orthogonal or parallel, and the uniaxial crystal is arranged between the first polarizer and the second polarizer; wherein:

The first polarizer is used to convert the received incident light carrying the information of the object to be measured into linearly polarized light polarized along a specified direction;

The uniaxial crystal is used to displace the left-handed circularly polarized light and the right-handed circularly polarized light generated by the linearly polarized light in opposite directions based on the photon spin Hall effect and/or angle dispersion effect;

The second polarizer is used to perform a sum or difference operation on the left-handed circularly polarized light field and the right-handed circularly polarized light field, so that when the displacement of the left-handed circularly polarized light field and the right-handed circularly polarized light is much smaller than the spot size , the transmitted light field is the first differential of the original incident light field.
The phase contrast microscope module based on uniaxial crystals according to claim 1, wherein the uniaxial crystals are uniaxial crystals of yttrium vanadate, lithium niobate, quartz, calcite, and BBO.
The phase contrast microscope module according to claim 1, wherein the left-handed circularly polarized light and the right-handed circularly polarized light with opposite spin directions produced by the uniaxial crystal are formed in the transverse direction by photon spin splitting. displacement.
The phase contrast microscope module according to claim 3, wherein the optical axis of the uniaxial crystal has a certain inclination angle relative to the beam propagation direction, and the displacement can be adjusted by changing the inclination angle.
The first polarizer and the second polarizer according to claim 1, wherein,

When the polarization states of the first polarizer and the second polarizer are orthogonal, the first-order differential of the incident light field in one dimension is realized;

When the polarization states of the first polarizer and the second polarizer are parallel, the first order differential of the incident light field in two dimensions is realized simultaneously.
A phase-contrast microscope device based on a uniaxial crystal, characterized in that it comprises an illumination module, an imaging module, and the phase-contrast microscope module according to any one of claims 1 to 5.
The phase-contrast microscope device based on uniaxial crystal according to claim 6, wherein the imaging module includes a first objective lens, a first focusing lens and a camera, and the phase-contrast microscope module is arranged on the first Between a focusing lens and the camera; the first objective lens is arranged in front of the first focusing lens.
The phase contrast microscopy equipment based on uniaxial crystal according to claim 7, wherein the illumination module comprises a light source, a second objective lens, and a second focusing lens; wherein, along the propagation direction of incident light, the second The objective lens is arranged between the light source and the second focusing lens; the light source is LED, halogen lamp or laser light source.
The phase contrast microscopy equipment based on uniaxial crystal according to claim 8, characterized in that, the phase contrast microscopy equipment also includes an object stage; the object stage is arranged between the first focusing lens and the second focusing lens. between an objective lens.
A phase contrast microscopy method based on the phase contrast microscopy equipment of uniaxial crystal according to any one of claims 6 to 9, characterized in that, comprising:

The light source emits incident light, and after the incident light is collimated by the second objective lens and focused by the second focusing lens on the object to be imaged on the stage, the first signal light is formed;

After the first objective lens collimates the first signal light, it is focused onto the camera by the first focusing lens. Before the signal enters the camera, it passes through the phase contrast microscope module;

The first polarizer transforms the received signal light into linearly polarized light polarized along a specified direction;

The uniaxial crystal is based on the photon spin Hall effect and/or angle dispersion effect, so that the left-handed circularly polarized light and the right-handed circularly polarized light generated by the linearly polarized light are displaced in opposite directions; wherein, the left-handed circularly polarized light and the right-handed circularly polarized light Circularly polarized light has an overlapping region, and the overlapping region contains both left-handed circularly polarized light and right-handed circularly polarized light;

The second polarizer performs a sum or difference operation on the left-handed circularly polarized light field and the right-handed circularly polarized light field to obtain the second signal light. When the displacement of left and right circularly polarized light is much smaller than the spot size, the second signal light is the first order differential of the original incident light field;

A camera records the second signal light to obtain phase contrast information of the object to be imaged.